The present invention relates generally to shutoff valves for liquid sprayers such as those used for insect control or lawn and garden use. In particular, the invention relates to valves that do not require a spring to hold the valve closed.
In the 1980's, H.D. Hudson Manufacturing Company developed a successful springless shut-off valve for liquid sprayers. In that sprayer valve, as explained in U.S. Pat. No. 4,933,569, the liquid travelled through a special reciprocating pin that was mounted for axial movement within a new valve body.
The valve body had a front section and a rear section. The front section had a downstream bore that communicated with a liquid nozzle. The rear section of the valve body had an upstream bore that could be attached to a liquid supply line and had three parts that each had different cross-sectional areas. The first part of the upstream bore had a relatively small cross-sectional area and communicated with a liquid supply inlet. The second part was downstream of the first part and had a larger cross-sectional area than the first part. The third part was downstream of the second part and had an even larger cross-sectional area.
A wall joined the two sections. A recess between two segments of the wall provided access to the upstream and downstream bores, as well as to a chamber on the opposite side of the bore.
The pin fit within the bores. It had a waist section that separated a downstream section and from three upstream sections. The downstream section fit within the downstream bore in the valve body, and had an o-ring that formed an upstream seal in that bore.
The first upstream section of the pin was sized to fit snugly within the first part of the upstream bore when the pin was in the closed position. When the pin was moved to the open position, the first upstream section retracted into the second part of the upstream bore, enabling liquid in the first part of the upstream bore to flow into the second part of the upstream bore.
The second upstream section of the pin had a larger cross-sectional area than the first section, and a second o-ring that provided a seal against the second part of the upstream bore when the pin was in the closed position. That section retracted into the third part of the upstream bore when the pin was moved to the open position, permitting liquid in the second part of the upstream bore to flow into the third part of the upstream bore.
The third upstream section of the pin fit within the third part of the upstream bore, had a larger cross-sectional area than the second section, and had a third o-ring that formed a downstream seal in the third part of the upstream bore.
A central passage extended through the pin, from an outlet that was located downstream of the first o-ring to inlets between the second and third o-rings. When the pin was in the open position, liquid could freely flow from the inlet, through the first, second, and third parts of the upstream bore, into the inlets, through the central passage, into the downstream bore, and then to the nozzle. In the closed position, the fit between the first upstream section of the pin and the first part of the upstream bore blocked the flow of liquid, with the second seal helping to prevent leakage.
A user moved the pin from the open position to the closed position by rotating a lever that was pivoted against an internal, upstream-facing shoulder in a radial groove in the chamber opposite the recess. The arm of the lever had a u-shaped notch with detents that engaged the waist of the pin, sliding across pin as the lever was pivoted and converting that rotational movement of the lever into linear movement of the pin.